This invention relates to power semiconductor components, for example a switch for automotive switching applications, comprising a power semiconductor device with a temperature sensor circuit. The power semiconductor device may be, for example, an insulated-gate field-effect transistor (hereinafter termed "MOSFET"), an insulated-gate bipolar transistor (hereinafter termed "IGBT"), or a bipolar transistor. The temperature sensor circuit can serve for sensing whether the device is approaching a thermal overload, and it may even be sufficiently sensitive for determining whether the device load is short-circuited.
United States Patent specification U.S. Pat. No. 5,563,760 (our reference PHB 33667) discloses a temperature sensor circuit for such power semiconductor devices comprising hot-location and cool-location temperature-sensitive elements in a comparator circuit. The whole contents of U.S. Pat. No. 5,563,760 are hereby incorporated herein as reference material. In particular, U.S. Pat. No. 5,563,760 discloses a circuit sensing a temperature gradient (Tdiff) threshold between the hot and cool locations. The circuit comprises (e.g. in FIGS. 5 and 6 of U.S. Pat. No. 5,563,760) temperature-sensitive elements serially arranged in first and second parallel arms which form a Wheatstone bridge arrangement in a comparator circuit and which are fed by current sources derived from a PTAT (proportional-to-absolute-temperature) voltage. The biasing of the arms via their respective PTAT current sources is arranged to render the temperature gradient threshold sensed by the Tdiff circuit either independent of the absolute (or actual) device temperature or a decreasing function of the device temperature based on a cool region of the device. The output of the comparator circuit provides a turn-off signal to the power semiconductor device in the event of an excessive Tdiff.
It is an aim of the present invention to provide an even more advantageous temperature sensor for a power semiconductor device, in which a Tdiff threshold sensed by a comparator circuit can decrease as a function of the device temperature at a hot location of the device.